Stiffener panels are known as panels that are conventionally employed for a wing structure, a fuselage structure, and the like of aircraft.
As a method of producing a composite material for such a stiffener panel, a method such as an integral molding method has been used.
For this integral molding method, the method according to JP 2647530 (Patent Literature 1) is known, which corresponds to an Application filed by the applicants of the present invention. In this molding method, a molding product raw material for a composite material is held by a holding tool having a shape for integral molding of composite material to integrally cure the entire material.
In this integral molding method, the strength of the composite material to be obtained is excellent because the entire molded product raw material is integrally cured. However, if the raw material for the stiffener has been liquefied, it may often be necessary to use complex jigs for maintaining the shape of the stiffener, and thus, the process may be burdensome.
On the other hand, as a method of producing a composite material for stiffener panels, a method such as a co-bonding method has been used.
In this co-bonding method, a panel or a stiffener that has been previously cured and molded, and the other that has not been cured and molded, are bonded using an adhesive, and the resultant is cured in an autoclave.
In this co-bonding method, because the panel or the stiffener has been previously cured, ease of handling of the molded product raw materials in production is excellent. However, because the strength of the composite material to be obtained depends on the strength of the bonding of the adhesive applied between the stiffener and the panel, it is necessary to devise measures to improve the quality of the bonding.